FIELD OF THE INVENTION
The present invention relates to an apparatus for and a method of detecting arc length, an apparatus for and a method of controlling welding torch height, and an automatic welder and an automatic welding method. More particularly, the present invention is concerned with an arc length detection method, a welding torch height control method and welding condition control method, as well as apparatus for carrying out these methods, suitable for use in automatic welding which makes use of a welding power supply having constant-voltage or constant-current characteristics.